1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device which makes flip chip bonding of a daughter chip at a mother chip, and makes flip chip bonding of a mother chip on a circuit board further, and particularly relates to a manufacturing method of a semiconductor device which can efficiently form solder balls to be used in order to make flip chip bonding of the mother chip on the circuit board.
2. Background Art
In recent years, the semiconductor device which has the COC (chip on chip) structure having made flip chip bonding of a daughter chip at a mother chip, and which made flip chip bonding of the mother chip further at the circuit board is proposed (for example, refer to Japanese Unexamined Patent Publication No. 2004-146728). Conventionally, when manufacturing this semiconductor device, after making flip chip bonding of the daughter chip on the circuit face of a mother chip, solder balls were formed on the circuit face of a mother chip, and flip chip bonding of the mother chip was made on the circuit board using these solder balls.
There are many solder balls to connect a circuit board with a mother chip, and for example, it is 1000 or more pieces. Therefore, in order to form solder balls efficiently, it is necessary to use the solder ball formation method of single wafer processing collectively enforced to a plurality of mother chips formed on the wafer.
As a solder ball formation method of such single wafer processing, there are a method of applying the resist to the circuit face of a mother chip, and making opening of the resist filling up with solder paste, and a method of laying a metal mask on top of the circuit face of a mother chip, and filling up opening of the metal mask with solder paste.
However, when forming solder balls in the manufacturing process of a conventional COC type semiconductor device, a daughter chip is connected and the surface of a mother chip is not flat. Therefore, since the resist could not be applied uniformly, and it was also difficult to process a thin metal mask according to the surface irregularity, the solder ball formation method of the above-mentioned single wafer processing was not able to be used.